Optical format with platform-and-well construction

ABSTRACT

Formats for optical analysis of fluid samples are provided with platforms and wells for contacting fluid samples and bringing reagents in contact with fluid samples. Formats may be made in opposing platform-and-well constructions, allowing a platform protruding from one format member to enter a well contained within an opposing format member. A sample fill nose accepts sample fluid from a sample collection opening and transports the sample fluid through the format.

Cross-Reference To Related Application

This application claims priority to U.S. Provisional Application No.60/515,338, filed on Oct. 30, 2003 which is incorporated by reference inits entirety.

FIELD OF THE INVENTION

The present invention relates generally to electrochemical analysis andmore specifically to an optical format for fluid analysis.

BACKGROUND OF THE INVENTION

Optical testing of samples has become increasingly popular in recentyears due to the speed, accuracy, and efficiency with which test resultscan be acquired through optical testing. Because of these benefits,optical testing is commonly used in medical applications such as glucosetesting, with the sample fluid being blood. Generally, optical testingin medical applications involves allowing light to interact with asample. In some applications, the sample may be combined with a reagentfor testing. Optical testing may be accomplished using “formats,” whichallow for the collection of a sample, combination of the sample with areagent, and optical testing of the sample.

Several problems arise in optical testing applications. A common problemwith sample testing is the necessary sample size to allow reaction witha reagent and enable accurate testing. Many optical formats requiresample sizes of 300 nl or greater. Further, optical formats often resultin performance errors due to poor mechanical tolerances of the formats.When a reagent is used with an optical format, the reagent may beinconsistently placed within the format. For example, an improper amountof reagent or reagent placed in the wrong location may affect testaccuracy. Formats resulting in improper control of sample volume—forexample, deposition of an insufficient sample volume within a testarea—decrease the accuracy of many prior art optical testing systems.Further, the costs of manufacturing optical formats can be high, andresulting formats are often larger than desired.

In order to increase the efficiency and accuracy of optical sampletesting, it is desirable to provide an improved optical format.

SUMMARY OF THE INVENTION

According to one embodiment of the present invention, an optical formatallows a very small sample volume to result in accurate optical testing.

According to some embodiments of the present invention, an opticalformat is provided which allows accurate optical testing of samplevolumes of approximately 50 nl.

According to some embodiments of the present invention, an opticalformat consists of two pieces designed to join into a single formatallowing accurate testing of small optical volumes.

According to some embodiments of the present invention, optical formatsallow the consistent placing of reagent within the optical format.

According to some embodiments of the present invention, reagentplacement is facilitated by the use of a mesa upon which a reagent isplaced during manufacturing of the format.

According to some embodiments of the present invention, sample volume ismetered to a required amount within an optical format before the sampleis allowed to react with a reagent within the optical format.

According to some embodiments of the present invention, an opticalformat is manufactured using continuous web processing to enablehigh-speed production of optical formats at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an optical format according to oneembodiment of the present invention;

FIG. 2 is an exploded perspective view of an optical format according toone embodiment of the present invention;

FIG. 3 is a top cross-sectional view along the line 3-3 of the opticalformat of FIG. 1; and

FIG. 4 is a side cross-sectional view along the line 4-4 of the opticalformat of FIG. 1.

While the invention is susceptible to various modifications andalternative forms, specific embodiments are shown by way of example inthe drawings and will be described in detail herein. However, it shouldbe understood that the invention is not intended to be limited to theparticular forms disclosed. Rather, the invention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 shows an optical format 10 according to one embodiment of thepresent invention. The optical format 10 may be used in the collectionand optical testing of samples, for example in medical testingapplications such as glucose testing or testing of other analytes inbiological fluid analysis. The optical format 10 may be created using avariety of fabrication techniques, such as micro-molding, coining, or UVreplication processes, and may be constructed of such materials aspolycarbonate, polystyrene, and polyester. Formats according to thepresent invention may be individually cut out of sheet material, cutinto one- or two-dimensional arrays, or cut into a circular discarrangement. Continuous web processing may be used to manufactureformats and format members according to the present invention, resultingin lower processing costs.

The optical format 10 comprises a first format member 12 and a secondformat member 14. Though the first and second format members 12 and 14are discussed in relation to top and bottom directions as shown in FIG.1, it is to be understood that these labels are for the purposes ofdiscussion and that the features of optical formats according to thepresent invention may be alternatively oriented in space—for example,features discussed in combination with the first format member 12 may beplaced on a lower format portion according to some embodiments of thepresent invention.

The second format member 14 shown in FIG. 1 is provided with a samplefill nose 16. The sample fill nose 16 provides for the collection ofsample fluid from a sample collection opening 18 and transport of thesample fluid from the sample collection opening 18 to a well 20. Thewell 20 is connected to a vent 22 provided with a vent opening 24. Inthe embodiment shown in FIG. 1, the sample collection opening 18 isprovided on a front face 26 of the optical format, and the vent opening24 is provided on a back face 28 of the optical format. According tosome embodiments of the present invention, sample collection openingsand vent openings may be provided on other faces of optical formats, orat face interfaces of optical formats, as required by particularapplications of the optical format.

According to some embodiments of the present invention, the sample fillnose 16 transports sample fluid from the sample collection opening 18 tothe well 20 via capillary action. The sample fill nose 16 is preferablyprovided with dimensions such that the open volume of the sample fillnose 16 is approximately equal to the volume of sample fluid requiredfor analysis within the well 20.

In an embodiment in which the sample fill nose 16 has a rectangularcross-section, the sample fill nose 16 has a height, h_(n), a width,w_(n), and a length, l_(n). According to one embodiment of the presentinvention, the volume of sample preferred for testing within the well 20is approximately 50 nl. In this embodiment, a sample fill nose 16 havinga height h_(n) of approximately 100 μm, a width w_(n) of approximately200 μm and a length, l_(n), of approximately 2.4 mm is appropriate tofill the well 20 with the desired amount of sample fluid. Thus, thesample volume is appropriately metered by the sample fill nose 16 duringsample collection. According to some embodiments of the presentinvention, it may be desirable to conduct testing with greater or lesseramounts of fluid, and the well 20 and the sample fill nose 16 may besized to enable optimum fluid transport to the well 20. The dimensionsof the format are dependent on the manufacturing process, but in generalthe maximum preferred sample volume of 1 μl limits the size of theformat.

According to some embodiments of the present invention, a platform 28 isprovided on an optical format member. The platform 28 is raised from aninner surface 30 of one of the optical platform members, as shown inFIG. 2. FIGS. 1 and 2 show the platform 28 extending downwardly from theinner surface 30 of the first platform member 12, but it is to beunderstood that optical formats according to the present invention mayemploy platforms extending upwardly from a bottom platform member. Inthe embodiment shown in FIGS. 1 and 2, the platform 28 extendsdownwardly from the inner surface 30 of the first optical format member12 and into the well 20 provided in the inner surface 32 of the secondoptical format member 14.

The platform 28 extends a height h_(p) from the inner surface 30 of thefirst format member 12. The platform 28 may be a circular platform witha diameter d_(p). According to one embodiment of the present invention,the height h_(p) of the platform 28 is approximately 50 μm and thediameter d_(p) of the platform 28 is approximately 1000 μm, but greateror lesser heights and diameters may be used in specific applications ofthe present invention. For example, heights ranging from about 25 μm toabout 250 μm and diameters ranging from about 500 μm to about 2000 μmare preferred in some embodiments of the present invention.

For the platform 28 to enter the well 20, the well 20 is provided with adiameter, d_(w) larger than the diameter d_(p) of the platform 28.According to one embodiment of the present invention, the diameter d_(w)of the well is approximately 1050 μm. Larger or smaller well diametersare possible. For example, well diameters ranging from about 550 μm toabout 2050 μm are preferred in some embodiments of the presentinvention. Further, the well is provided with a depth h_(w) that isdeeper than the height h_(p) of the platform 28, thereby forming asample testing region 34, most easily seen in FIG. 4. According to oneembodiment of the present invention, the sample testing region 34 has aheight h_(l) of approximately 50 μm. Larger or smaller testing regionheights are possible. For example, testing region heights ranging fromabout 25 μm to about 100 μm are preferred in some embodiments of thepresent invention.

The vent 22 extends from the sample testing region 34 toward the rearface 36 of the optical format 10. According to some embodiments of thepresent invention, the vent 22 serves to ensure capillary movement ofsample from the sample collection opening 18 toward the sample testingregion 34. The vent 22 of the embodiment shown in FIGS. 1-4 has arectangular cross-section with a height h_(v), a width w_(v) and alength l_(v). According to one embodiment of the present invention, theheight h_(v) of the vent is approximately 100 μm, the width w_(v) of thevent is approximately 500 μm, and the length l_(v) of the vent isapproximately 400 μm. Other vent dimensions are contemplated in otherembodiments of the present invention. For example, vent heights rangingfrom about 50 μm to about 200 μm, vent widths ranging from about 50 μmto about 200 μm, and vent lengths ranging from about 50 μm to about 500μm are preferred in some embodiments of the present invention. Inaddition to increasing capillary force in the capillary gap of thesample testing region 34, the vent 22 may provide an area for sampleoverfill.

The platform 28 may be provided with a reagent thereon designed to reactwith the sample in the sample testing region 34. Reagent may be placedon the platform via pump depositing, or by methods such as printing, pindeposition, or ink jetting. A reagent may be retained on the platform 28by oven-drying before assembly of the optical format 10. According toone embodiment of the present invention, a reagent is deposited on theplatform 28 before the optical format members are joined together. Inthis embodiment of the invention, the platform 28 keeps the reagent fromspreading beyond the platform 28 or the sample testing region 34.Further, when a reagent is uniformly deposited on the platform 28, auniform thickness of reagent and a uniform reaction area are achieved.According to some embodiments of the present invention, reagent combineswith a sample within the sample testing region 34 to result in acolormetric reaction. The resulting color may be analyzed using diffusereflectance or transmission through the sample.

According to some embodiments of the present invention, adhesive isprovided between the format members to glue the first format member 12to the second format member 14. In one embodiment of the presentinvention, heat-activated optically-clear adhesive is coated onto theinner surface of one or both of the format members for adhesion of theformat members.

According to some embodiments of the present invention, top and bottomoptical format members both comprise optically clear material. Theseembodiments may be used for optical transmission or diffuse reflectanceanalysis. Alternatively, one of the optical format members may compriseoptically reflective material. Embodiments using optically reflectingmaterial may be used in optical analysis based on diffused or reflectedlight from a sample.

The formats and methods of the present invention allow for the efficientconstruction of small and reliable optical formats. As shown in FIG. 1,a format has a format length l_(f), a format width w_(f), and a formatheight h_(f). According to one embodiment of the present invention, theformat length is approximately 3.85 mm, the format width isapproximately 3 mm, and the format height is approximately 1 mm. Formatshaving other dimensions may be preferred in some embodiments of thepresent invention. For example, format lengths ranging from about 3.00mm to about 12.5 mm, format widths ranging from about 2.00 mm to about5.00 mm, and format heights ranging from about 0.50 mm to about 3.00 mmare preferred in some embodiments of the present invention. Opticalformats according to the present invention may be designed for handlinga wide range of sample fluid volumes. For example, sample volumes fromabout 5 nl to about 1000 nl are contemplated in some embodiments of thepresent invention. While the present invention has been described withreference to one or more particular embodiments, those skilled in theart will recognize that many changes may be made thereto withoutdeparting from the spirit and scope of the present invention.

For example, while the present invention has been generally described asdirected to medical applications it is to be understood that otheroptical fluid testing applications might employ the principles of theinvention. Each of these embodiments and obvious variations thereof iscontemplated as falling within the spirit and scope of the claimedinvention, which is set forth in the following claims.

1. A format for optical testing of a sample comprising: a first formatmember comprising a first inner surface and a platform extending adistance from said inner surface; a second format member comprising asecond inner surface and a well disposed within said second innersurface, said well having a predetermined volume and shaped to acceptsaid platform of said first format member within said well, saidplatform filling a significant portion of said predetermined volume suchthat said well and said platform define a sample testing region having asample testing region volume significantly less than said predeterminedvolume and having a predetermined sample testing region height; a samplefill nose disposed within said second format member and extending from asample collection opening at a first end of said sample fill nose tointersect with said well at a second end of said sample fill nose; and avent disposed within said second format member and extending along saidsecond inner surface from a vent opening at a first end of said vent tointersect with said well at a second end of said vent, wherein saidsample fill nose has a sample fill nose cross-section and said vent hasa vent cross-section different from said sample fill nose cross-section,said vent configured to receive sample overfill from said sample testingregion via said second end of said vent.
 2. The format of claim 1wherein said second end of said vent intersects with said well at anarea approximately opposing the intersection of said second end of saidsample fill nose with said well.
 3. The format of claim 1 wherein saidplatform extends from said first inner surface to a platform height andwherein said well extends within said second format member to a welldepth greater than said platform height, the difference of said welldepth and said platform height defining said sample testing regionheight.
 4. The format of claim 1 wherein said platform is provided witha reagent thereon for reacting with said sample.
 5. The format of claim3 wherein said sample fill nose has a fill a fill nose volume greaterthan said sample testing region volume.
 6. A format for optical testingof a sample comprising: a first format member comprising a first innersurface and a platform extending to a platform height from said innersurface; a second format member comprising a second inner surface and awell disposed within said second inner surface and extending a welldepth below said second inner surface, said well having a first volumeand shaped to accept said platform of said first format member withinsaid well, said platform filling a significant portion of said firstvolume of said well thereby forming a sample testing region having apredetermined sampling volume that is significantly less than said firstvolume; a sample fill nose extending from a sample collection opening ata first end of said sample fill nose to said well at a second end ofsaid sample fill nose; and a vent extending from a vent opening at afirst end of said to said well at a second end of said vent, whereinsaid sample fill nose has a sample fill nose cross-section and said venthas a vent cross-section different from said sample fill nosecross-section, said vent configured to receive sample overfill from saidsample testing region via said second end of said vent.
 7. The format ofclaim 6 wherein said platform is cylindrical and has a platform diameterand said well is cylindrical and has a well diameter greater than saidplatform diameter.
 8. The format of claim 6 wherein said sample fillnose is adapted to transport a volume of said sample from said samplecollection opening to said sample testing region via capillary action.9. The format of claim 8 wherein said volume of said sample isapproximately 50 nl.
 10. The format of claim 8 wherein said volume ofsaid sample is within the range of from approximately 5 nl toapproximately 1000 nl.
 11. The format of claim 7 wherein said ventopening is provided on an opposite side of said format from said samplecollection opening.
 12. A method of manufacturing a format for opticaltesting, the method comprising the acts of: providing a first formatmember comprising a first inner surface and a platform extending to aplatform height above said first inner surface; providing a secondformat member comprising: a) a second inner surface and a well disposedwithin said second inner surface and extending to a well depth belowsaid second inner surface, said well depth being greater than saidplatform height, said well having a first volume; b) a sample fill nosenotch having a first width, said sample fill nose notch terminating atsaid well; and c) a vent notch having a second width different that saidfirst width, said vent notch terminating at said well; and joining saidfirst format member to said second format member by inserting saidplatform of said first format member into said well of said secondformat member, said platform filling a significant portion of said firstvolume of said well thereby forming a sample testing region having asample region volume that is significantly less than said first volume,wherein said vent notch is configured to receive sample overfill fromsaid sample testing region.
 13. The method of claim 12 furthercomprising applying a testing reagent to said platform.
 14. The methodof claim 12 wherein said sample fill nose notch approximately opposessaid vent notch across said well.
 15. The method of claim 12 furthercomprising providing adhesive on one or both of said first and secondformat members.
 16. The method of claim 12 wherein said vent notch has arectangular cross-section.
 17. The method of claim 12 wherein said fillnose notch has a rectangular cross-section.
 18. A format for opticaltesting of a sample comprising: a first format member comprising a firstinner surface and a platform extending a distance from said innersurface in a direction substantially perpendicular to said innersurface; a second format member comprising a second inner surface and awell disposed within said second inner surface, said well being shapedto accept said platform of said first format member within said well,said well and said platform defining a sample testing region having afirst volume; and a sample fill nose disposed within said second formatmember and extending from a sample collection opening at a first end ofsaid sample fill nose to intersect with said well at a second end ofsaid sample fill nose, said sample fill nose having a second volumeapproximately equal to said first volume.
 19. The format of claim 1wherein said vent cross-section has a first area and said sample fillnose cross-section has a second area, said first area is greater thansaid second area.
 20. The format of claim 8 wherein said ventcross-section has a first area and said sample fill nose cross-sectionhas a second area, said first area is greater than said second area. 21.The method of claim 12 wherein said first width is greater than saidsecond width.
 22. The format of claim 1 wherein said platform extends ina direction substantially perpendicular to said inner surface.